A normative ethics with universal, symmetric and functional rules is based upon the fundamental principle of property rights. The ethics of freedom and property rights is the natural law, the system of norms adequate to human nature that permits harmonious and peaceful social coexistence and development by avoiding, minimizing or solving conflicts as much as humanly possible.

Property is the domain of legitimate decision by the owner, the space in which each person is free to act according to his preferences without violent interference from others, whose valuations in this regard are ethically irrelevant. All peaceful actions by the owner in his property are permitted, and no actions are obligatory (there are no natural positive duties). The right to property is a negative right of non interference. Humans do not have natural positive rights that imply that others must do something for them, and there are no natural duties towards others (present or future). Positive rights and duties arise by means of contracts.

Freedom does not mean absolute absence of restrictions: my freedom ends where the freedom of others begins; my property is finite and limited by other people’s properties. Freedom and property rights are equivalent to the non aggression axiom: the initiation of force is not legitimate; force may be used only for defense and justice. Aggression, the invasion of the property of others without their consent, is forbidden. The aggressor must repair the damages and compensate the victim.

Aggression is not only the narrow sense notion of criminal violence performed by a person against another one and his possessions (murder, assault, injuries, rape, kidnapping, theft). Aggression in an abstract sense is any sufficiently intense adverse or noxious physical interference caused by a person or his possessions on another person’s property.

Property, being the owner of something, is not always good: property does not only imply the right to enjoy and use means of action. Property can be bad: the owner is responsible for the damages that his actions and his possessions could cause on others (intended or unintended, known or unknown, foreseen or unforeseen). All actions imply the production of undesired residuals or waste that must be taken care of by the owner so that they do not damage others.

All real things are directly or indirectly interconnected by fundamental forces, so that a change in one entity causes some effect, small or big, on other entities. But ethical rules refer only to changes and effects caused by human action that can damage others and create conflicts. These interactions can involve matter (solid, liquid, gas; macroscopic or microscopic particles), energy (heat, electromagnetic waves, pressure waves) or alterations of natural environmental conditions (phenomena like luminosity, pressure, temperature, winds, humidity). Effects can be more or less strong or weak, concentrated or diffuse, direct or indirect, local or global, frequent or infrequent, cumulative or non cumulative, instantaneous or delayed, temporary or permanent.

Due to the limitations of the human mind, reality is often studied in a simplified way as if it were linear and simple: but nature is in fact a complex network of entities and relationships. A cause can have multiple effects over different persons, some positive and some negative. An effect can have multiple causes, natural or artificial, from one person or from many people doing the same thing (like breathing) or complementary things (like making and driving cars, or like producing and consuming energy). In chaotic non linear systems, small causes can have big effects (due to amplifiers, destabilizers, or positive feedback loops), but also big causes can have small effects (due to dampers, stabilizers or negative feedback loops).

In order to be qualified as aggressions, real events must at least be physically detectable, psychologically perceptible and relevant for human preferences. Objective real conditions do not automatically constitute problems. It is human valuations which perceive situations as opportunities or threats, benefits or damages, goods or bads. And it is the possible incompatibility of subjective human preferences what originates conflicts: what one likes another may dislike.

The specific contents of the notion of aggression are somehow open and debatable; it is not a concept with sharp boundaries, it is partially fuzzy and arbitrary. It cannot be fully determined by deduction using pure reason, it depends on customs, traditions, conventions (blocking sunlight, high intensity lights, high volume sounds, pollutants). Some objective criteria can be used to determine whether an event is more adequately considered an aggression or not: intensity, directness, extension, duration, accumulation.

A functional ethics of freedom needs to include responsibility principles and rules for legitimate defense. The traditional and sensible principles of justice place the burden of proof of aggression on the accuser, who must prove beyond reasonable doubt the guilt of the accused. It is not the accused who must prove his innocence (if it were so, every person should have proof of innocence for every action and moment in his life, because he could always be accused of something). Legitimate defense may be invoked by the actual or possible receiver of the effects of an action if there is clear, present and provable danger, and not just if someone cannot fully assure that there is not. Defense becomes illegitimate (it becomes aggression) if it cannot be proved that there is a danger of real damage.

The precautionary principle proposed by many environmentalists demands that the initiator of an activity proves its complete harmlessness and that the government does not need to prove probable harm in order to stop it. Proving that something is absolutely innocuous is impracticable in new domains, where learning is performed by trial and error, and therefore this principle would paralyze innovation. Knowledge acquisition is costly and full knowledge is impossible.

The notion of aggression is based on the consequences or results of actions (the real effects in the world), and not on the knowledge or intentions of the agents. Instinctive moral feelings tend to excuse or diminish responsibility if there is no intentionality or if the damages are unforeseen secondary effects: this is so partly because moral feelings evolved as genetic instincts in past times when our human ancestors had little capabilities of action. But with capital and technological accumulation it is necessary to demand responsible use of powerful tools, and warn persons that their ignorance or lack of foresight will not excuse them for the damages they might cause. This kind of rules provide incentives for agents to fully consider all possible consequences of their actions, and not only the ones they intend to achieve, because they will be judged according to the real effects of their actions.

Property rights work very well when reality is easily separable, when the effects of actions are direct, local, concentrated, and falling mainly on the owner and his property and eventually on adjacent others easy to identify. But elements of reality are often intertwined in messy ways. Solid macroscopic objects tend to stay in their stable positions; but fluids (liquids and specially gases) tend to move, and photons and thermal energy tend to flow, they spread and cross legal boundaries unless stopped by some physical barrier.

Externalities are effects of actions of an agent on the property of others; they can be positive (like gifts, not forbidden and not obligatory) or negative. An aggression is a negative externality. Diffuse negative externalities are problematic and difficult to regulate. Many victims could suffer a very small nuisance or loss from the actions of one agent: it might seem ridiculous to consider illegitimate actions that produce such small effects and it would be very costly for each of the victims to demand the agent to stop or compensate them. Externalities can become important due to the cumulative and persistent effects of small actions of many agents. In a clear aggression it is possible and relatively easy to determine who is doing what to whom, who must be stopped or who must compensate whom for what. In diffuse externalities it can be very difficult to determine and connect agents, actions, effects and receivers of effects.

Since aggressions imply damage, it might be naively considered that it is better to make it a very inclusive notion, so that many losses are avoided. But accepting that something is an aggression and forbidding it has consequences that might be worse than simply tolerating it. The more actions are considered illegitimate aggressions, the more use of force is justified. Costs of the system necessary to detect and punish the aggressors and compensate the victims could exceed its benefits (always bearing in mind that it is extremely problematic to perform interpersonal comparisons and additions or subtractions of utility or social cost-benefit analysis). It might be better to learn to live with some changing realities, to adapt to them, than to try to avoid them. Especially because humans are good at adaptation, by means of which they have colonized most of the planet with very different environmental conditions.

Automatically giving the State the responsibility to deal with diffuse negative externalities can be a huge mistake. The State is the monopoly of jurisdiction and violence, and it is often illegitimate (dictators, or even democratic leaders according to anarchists), very inefficient and possibly corrupt (lack of motivation or incentives and lack of knowledge or impossibility of socialism, public choice theory).

What is often called market failure is often just the result of inadequate determination of property rights. Markets are never perfect because human beings are limited in their abilities; proposing that the State fixes alleged problems that individuals cannot solve freely seems to forget that the State is also made up of humans, and perhaps not the best ones (bureaucrats are not disinterested angels, and the worst might get to the top).

Climate change

Ethics concerns only human beings: there is no natural duty to preserve the environment, which has no intrinsic value because valuations are products of the mental activity of cognitive emotional agents.

Contamination above certain levels is usually considered an illegitimate aggression because pollutants directly damage human beings and have no beneficial effects. Climate change is related to the environment but it is very different from contamination.

Anthropogenic climate change might occur due to changes in land use and emission of greenhouse gases. Changes in land use can alter the reflectivity or albedo of the surface of the planet, and it seems hard to consider them an illegitimate action. Carbon dioxide is a greenhouse gas that results from respiration and from burning fossil fuels; labeling it as a contaminant is an abuse of language, since it is necessary for photosynthesis and it is not toxic. Some human activities, like growing trees, take carbon dioxide off the atmosphere. It is extremely difficult to prove specific relationships between human carbon dioxide emissions, local climate changes and its particular effects.

Climate change, be it global warming or cooling, has multiple possible causes and effects, and the valuation of the effects can be different in different parts of the planet. Cold regions may welcome warming and lament cooling, warm regions may welcome cooling and lament warming. Climate change alarmists seem to be climate reactionaries accepting no change. There is no optimal climate, and conflicts for its determination may arise if humans achieve partial control over it. Even if humans are adapted to the present climate, this does not imply that it would be difficult to adapt to different climates if the changes are not excessive.

Climate change could happen quickly on a geological scale, but it is slow on a human scale, permitting informed adaptation and planning for the future. Climate change mitigation policies have certain huge costs in the present and would provide uncertain small benefits in the future. The relatively poor of today would sacrifice to help the relatively rich of tomorrow.

Temperature is not the only phenomenon associated with climate change and it is possibly not the most relevant for human welfare, since humans live in wide ranges of temperature. Sea level, precipitations, and extreme weather events can be much more important.

Sea level can slowly increase due to global warming, but the process is very slow, so that protections can be prepared and capital amortized if necessary; freedom of migration can help relocate people whose lands become inhabitable. Precipitations should in general increase with global warming, although their distribution might change. And the dependence of extreme weather events on temperature is complex and little known.

For almost all human problems associated with global warming, the influence of climate on them is usually small if compared with other more important factors that can be more easily and efficiently dealt with. Climate change alarmists seem to ignore relatively simple solutions for the problems they raise. Humans are proactive, they do not passively submit to natural influences, and the avoidance of climate change is not necessarily the best option.

Fresh water is a problem where there are no property rights, markets and prices for water. Tropical diseases depend strongly on socioeconomic conditions. Undeveloped nations are poor mostly due to inadequate social institutions, not because of environmental conditions. Heat waves can be dealt with by means of proper air conditioning (and global warming would reduce cold waves and their associated deaths). The extinction of species is mostly due to habitat destruction or invasion by humans (or direct killing, hunting or fishing).

Global warming catastrophists seem to forget other more important and urgent issues which compete for the allocation of the scarce resources demanded for climate change mitigation. It is preposterous to declare global warming the worst problem for mankind when there is war, hunger, sickness, poverty.

For some radical environmentalists and many politicians, climate change is the most important problem for human civilization, and they pretend to speak in the name of all mankind. But all problems seem to be extreme for them, having no notion of relative opportunity costs. Their moral language imposes duties on citizens who seem to be receiving orders about what they must do and what they must avoid no matter what.

Governments are supposed to be necessary to protect their citizens against aggressions, but they are very incompetent at this task, they often perform their own institutional aggressions by prohibiting perfectly peaceful and voluntary activities, and now with climate change they seem to consider anthropogenic global warming an illegitimate undesirable action. Some radicals even try to censor and criminalize dissent from skeptics, deniers or minimizers. But thought and speech, even if wrong or false, are never real crimes. There may be special interests groups on both sides of the debate fighting for their favorite public policies: not only oil and coal and nuclear companies, but also heavily subsidized renewables.

While the official mainstream climate science may well be correct, the ignorance regarding economics, political philosophy and law is huge. The most important entities for a human being are other human beings (for the good and for the bad), and not the environment. Humans can be especially damaging when organized politically and inspired by collectivism. The possible damages of climate change should be compared to the possible damages of governmental bureaucratic intervention and political oppression. Maybe the whole global warming scare is an excuse to increase the extension of political power or a distraction from other serious problems. Social institutions matter most, and they are very wrong now: a huge improvement is possible, and freedom is the answer.

Many libertarians know much about economics, law and ethics but are very weak on natural sciences. Michael Shermer is a brilliant intellectual who knows about both natural and social sciences, a great combination of intelligence and freedom.